!PLEASE HELP! !URGENT! 25 POINTS

What process in stars played a role in the formation of the universe?

a) evoluton

b) nuclear reactions

c) photosynthesis

d) radiation

Answer:

C₃H₈ has a higher boiling point than C₂H₆

Explanation:

The boiling point is the temperature at which the intermolecular bonds holding molecules in liquid form are overcome and change the state into a gas. C₃H₈ experiences stronger intermolecular bonds then C₂H₆ because it has more carbons. While the strength of each bond is the same between the two molecules, C₃H₈ has more opportunities to create these bonds due to the higher carbon count.  The more bountiful the intermolecular bonds, the more energy is needed to overcome them all. Thus, C₃H₈ has a higher boiling point.

Answer:

1) Change HCl into 2HCl

2) Change HCl into 2HCl

3) Change Al into 8Al, Fe3O4 into 3Fe3O4, Al2O3 into 4Al2O3 and Fe into 9Fe

4) Change HBr into 2HBr

5) Change NaI into 2NaI and Na2S2O3 into 2Na2S2O3

6) Change LaCl3 into 2Lacl3, Na2CO3 into 3Na2Co3 and NaCl into 6NaCl

Answer:

thermal shock

Explanation:

the temperatures inside the glass jar should have continued to increase over time. Internal stresses due to uneven heating. This is also known as “thermal shock”.

In general, the thicker the glass, the more prone it will be to breaking due to the immediate differences in temperature across the thickness of glass.

Borosilicate glass is more tolerant of this, as it has a higher elasticity than standard silicon glass.

You may also note that laboratory test tubes and flasks are made with thinner walls, and of borosilicate glass, when designated for heating.

Answer:

The protons

Explanation:

The force of attraction/repulsion is indirectly proportional to the square of the distance between...the protons are much closer together and will have a stronger force.

F = k q1q2 / r^2

Answer:

137.2 L

Explanation:

p1v1 = p2v2

p1v1 / p2 = v2

98 * 35  / 25 = v2 = 137.2 L

To find the volume of the balloon when the atmospheric pressure is 25.0 kPa at a height of about 25 km, we can use Boyle's Law,as per which volume is 137.2 L.

Boyle's law is an experimental gas law which describes how the pressure of the gas decreases as the volume increases. It's statement can be stated as, the absolute pressure which is exerted by a given mass of an ideal gas is inversely proportional to its volume provided temperature and amount of gas remains unchanged.

Boyle's Law equation: P₁  V₁ = P₂  V₂

Given:

P₁= 98.0 kPa (initial pressure of the balloon)

V₁ = 35.0 L (initial volume of the balloon)

P₂ = 25.0 kPa (final atmospheric pressure)

V₂= unknown (final volume of the balloon)

Plugging in the values into Boyle's Law equation, we have:

98.0 kPa × 35.0 L = 25.0 kPa × V₂

To find V₂, we can rearrange the equation:

V₂ = \(\dfrac{98}{35}\times{25}\\=137.2 \ L.\)

Therefore, the volume of the balloon when the atmospheric pressure is 25.0 kPa at a height of about 25 km is approximately 137.2 L.

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The values given in the question, [K+]in is 20-30 times greater than [K+]out. Assuming [K+]out is 5mM (millimolar), the potential difference would be approximately -90mV to -100mV.

To calculate the potential difference between the inside and outside of a neuron solely due to the imbalance of potassium ions, you would use the Nernst equation. The equation is E = RT/zF * ln([K+]out/[K+]in), where E is the potential difference, R is the gas constant, T is the temperature, z is the charge of the ion, F is Faraday's constant, [K+]out is the concentration of potassium ions outside the cell, and [K+]in is the concentration of potassium ions inside the cell.



You do not need to know the standard reduction potential of K to solve this problem.

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The relationship between Keto and enol tautomers  is the interconversion between a keto group and an enol group. and curcumin can exist in both forms.

Keto-enol tautomerism is a type of isomerism in which a molecule exists in two forms, the keto form and the enol form, that are in equilibrium with each other.

For example: Curcumin, a natural polyphenol found in turmeric, can exist in both keto and enol forms due to the presence of an α,β-unsaturated carbonyl group.

Tautomers, are interconvertible by the transfer of a hydrogen atom and a double bond. In the keto form, the molecule contains a carbonyl group (C=O), while in the enol form, the molecule contains an alkene (-C=C-OH) and an alcohol (-OH) group. Curcumin, which is the main active ingredient in turmeric, is an example of a compound that can exist in both the keto and enol forms. The keto form of curcumin is more stable and is the predominant form in solid-state, while the enol form is more reactive and can undergo various reactions.

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Answer:

Option d is correct

Explanation:

The basis of the VSEPR model of molecular bonding is that to minimize repulsions, electron domains in the valence shell of an atom arrange on their own.

According to VSEPR theory, if there are two electron domains on a central atom, they will be arranged such that the angles between the domains are 180°

The hydrated ions are free to move around when ionic salts dissociate in aqueous solutions. Their movement, however, is random, and there is no charge.

After separating a solid substance into its ions, the ions are ready for reactions. When a compound is solid, the ions are held together by electrostatic attractions. To allow ions to move freely, it must first be dissolved in solution. Consider the reaction between sodium chloride and silver nitrate. Both of these compounds are commonly available in solid form. First, you would dissolve both solids in a solution, in this case water. (See Equations 1 and 2)

Once the solid has dissolved and separated into its ions in solution, these ions are ready to react in the chemical reaction (Equation 3).

Keep in mind that the AgNO3(aq) and NaCl(aq) reactants demonstrate that the ions are in solution. In other words, AgNO3(aq) is the same as Ag+(aq)+NO3(aq), and NaCl(aq) is the same as Na+(aq)+Cl (aq). The equation in Equation 3 represents a double displacement reaction, which means that cations in the reactants exchange anions to form the products. A precipitate is formed in the laboratory that we identify as silver chloride.

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Answer:

Divide the mass of 60 g by the molecular weight. That gives you the number of moles of NO2. Multiply the number of moles of NO2 by Avogadro's number, which is 6.02 x 1023. That gives you the number of molecules of NO2.

Answer:

whoa this question is long

Explanation:

how did u write it gosh

okay this time for real: C im pretty sure

Explanation:

The minimum volume of 0.282 M KI solution required to completely precipitate all of the lead in 165.0 mL of 0.150 M Pb(NO3)₂ solution is 87.8 mL.

The chemical reaction that takes place when a potassium iodide solution is added to lead (II) nitrate solution is given as follows:

Pb(NO3)₂ + 2KI → 2KNO₃ + PbI₂

From the chemical reaction, it can be seen that 2 moles of KI will react with 1 mole of Pb(NO3)₂ to yield 1 mole of PbI₂. The number of moles of lead nitrate in the given volume can be calculated as follows:
n = M × V

n = 0.150 M × 165.0 mL/1000

n = 0.02475 moles

The number of moles of KI required to precipitate all the lead can be calculated as follows:

n = 0.5 × 0.02475

n = 0.012375 moles

The volume of 0.282 M KI solution required can be calculated as follows:

V = n × M-1

V = 0.012375 moles × 0.282 L/mole

V = 0.00349 L

V = 3.49 mL

V = 87.8 mL (rounded off to three significant figures)

The answer is that 87.8 ml of 0.282 M potassium iodide solution is required to completely precipitate all of the lead in 165.0 ml of a 0.150 M lead (II) nitrate solution.

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Answer:

4.50 L gas of fluorine at STP contain 0.2 moles.

Explanation:

Given data:

Volume of gas = 4.50 L

Number of moles F₂ gas  = ?

Temperature of gas = standard =  273.15 K

Pressure of gas = standard = 1  atm

Explanation:

Formula:

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

Now we will put the values in formula.

1 atm × 4.50 L = n × 0.0821 atm.L/ mol.K  × 273.15 K

4.50 atm.L  = n × 22.43 atm.L/ mol.

n = 4.50 atm.L   / 22.43 atm.L/ mol.

n = 0.2 mol

4.50 L gas of fluorine at STP contain 0.2 moles.

Lithium is used to build computer batteries, whereas iron is used in industry to construct buildings and bridges.

In engineering, metals are characterized to have electrical conductivity and other properties (e.g., ductility, reflectivity, etc).

For example, Lithium can be defined as soft metal (alkali metal) that is suitable to store electrical energy.

In conclusion, Lithium is used to build computer batteries, whereas iron is used in industry to construct buildings and bridges.

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The general equation for the reaction between alkali metal and water is represented as:

M(s) + H₂O(l) → MOH(aq) + 1/2H₂(g)

Alkali metals react with water to form metal hydroxides and hydrogen gas. The reaction is exothermic and it occurs more vigorously with the increase of atomic size of the alkali metal. The reactivity of alkali metals with water increases down the group due to a decrease in ionization energy and an increase in atomic size. The larger atomic size of the alkali metal allows for the electron to be farther from the nucleus, and therefore it is easier to lose the electron.

The products of the reaction between alkali metal and water include metal hydroxide and hydrogen gas. The alkali metal hydroxide is a basic solution. For example, sodium reacts with water to produce sodium hydroxide and hydrogen gas.

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The energy required to ionize a hydrogen atom is 0.544 electronvolts (eV).

What is ionization energy?

Ionization energy, also known as ionization potential, is the amount of energy required to remove an electron from an atom or a positively charged ion. It is the minimum energy necessary to completely remove an electron from its orbital and create a positively charged ion.

To determine the energy required to ionize a hydrogen atom when its electron is in the n=5 state, we need to find the energy difference between the n=5 energy level and the ionization energy level, where the electron is completely removed from the atom.

The ionization energy of a hydrogen atom can be calculated using the formula:

Ionization Energy = \(\frac{-13.6 eV }{n^2}\)

Where n is the principal quantum number of the energy level.

For the n=5 energy level, the ionization energy would be:

Ionization Energy = \(\frac{-13.6 eV}{5^2}\)

Ionization Energy =\(\frac{ -13.6 eV}{25}\)

Ionization Energy = -0.544 eV

Since the energy values are typically expressed as positive values, we can take the absolute value of the result:

Ionization Energy = |-0.544 eV|

Ionization Energy = 0.544 eV

Therefore, the energy required to ionize a hydrogen atom when its electron is in the n=5 state is 0.544 electronvolts (eV).

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The ligand field splitting energy in the [V(OH2)6]3 complex is 21,000 cm-1, or 259 kJ/mol.

The green color and absorption of light at 560 nm suggest that the [V(OH2)6]3 ion has undergone a ligand field transition from its ground state to an excited state. The ligand field splitting energy, denoted as Δ, is the energy difference between the two states. We can use the relationship between energy and wavelength, E = hc/λ, where h is Planck's constant, c is the speed of light, and λ is the wavelength, to calculate the energy of the absorbed light.

E = hc/λ = (6.626 x 10^-34 J s) x (3.00 x 10^8 m/s) / (560 x 10^-9 m) = 3.55 x 10^-19 J

To convert this energy to units of cm-1, we use the relationship E = hcν, where ν is the frequency.

ν = E/hc = (3.55 x 10^-19 J) / (6.626 x 10^-34 J s x 3.00 x 10^8 m/s) = 1.77 x 10^14 Hz

The frequency in units of cm-1 is obtained by dividing by the speed of light in cm/s.

ν(cm^-1) = ν/ c = (1.77 x 10^14 Hz) / (3.00 x 10^10 cm/s) = 5,900 cm^-1

Finally, we use the Tanabe-Sugano diagram or empirical equations to relate the ligand field splitting energy to the frequency. For the [V(OH2)6]3 complex, the ligand field splitting energy is 21,000 cm^-1, or 259 kJ/mol.

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In the polysaccharide cellulose, large numbers of monosaccharides are linked together through glycosidic linkages.

TPolysaccharides, which are the most ubiquitous carbohydrates in nature, serve a number of functions, including energy storage and incorporation into plant cell walls.

Tens to thousands of monosaccharides are joined together via glycosidic linkages to form large polymers known as polysaccharides. The three most frequent polysaccharides are starch, glycogen, and cellulose. They are collectively referred to as homopolymers because, after complete hydrolysis, each of these three exclusively yields one type of monosaccharide (glucose).

Heteropolymers may also comprise sugar acids, amino sugars, or non-carbohydrate substances in addition to monosaccharides. Polysaccharides, a class of non-reducing carbohydrates, are not sweet and do not change. 

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Answer:

0.0111mol/L

Explanation:

M = n/V

We don't know n, but we know that n =mass/Molar mass, so:

n = 8.77g/166.0028 g/mol

n = 0.0528304342mol

M = n/V

M = 0.0528304342mol/ 4.75L

M = 0.111221967mol/L

Round to three sig figs if necessary: 0.0111mol/L

The molarity of the solution is 0.010M.

Molarity:

Molar concentration is a measure of the concentration of a chemical species, in particular of a solute in a solution, in terms of amount of substance per unit volume of solution.

Given:

Mass=8.77g

Volume= 4.75 L

To find:

Molarity=?

Firstly we need to calculate the number of moles.

Molar mass of KI=  166 g/mol

Given mass= 8.77 g

\(\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}} \\\\\text{Number of moles}=\frac{8.77}{166}= 0.05 \text{mol}\)

Now, substituting the values in molarity formula which is given as:

\(\text{Molarity}=\frac{n}{V} \\\\\text{Molarity}=\frac{0.05}{4.75} =0.010M\)

Therefore, the molarity of the solution is 0.010M.

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A GEL is a semisolid preparation that contains very small solid particles that are suspended in a liquid. A gel always contains an agent (e.g., agarose) that provides stiffness to the preparation.

A gel is a semisolid preparation that contains a gelling agent which provides stiffness to the preparation.

The gelling agent can be, for example, agarose (this gelling agent is used to prepare gels in electrophoresis).

In an agarose gel, agarose molecules are organized into three-dimensional (3D) structures similar to pores, which allow the passage of DNA fragments during electrophoresis.

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The rate of a chemical reaction is determined by how quickly the reactants disappear and the products appear.

The rate of a chemical reaction is defined as the change in concentration of reactants or products over time. The rate is determined by the frequency of successful collisions between the reacting molecules, which in turn depends on various factors such as temperature, concentration, surface area, and the presence of a catalyst.

Factors such as how quickly the scientist can stir the reaction or how quickly the reaction gets hot or cold may affect the reaction rate indirectly by affecting these factors that determine the rate. However, the primary factor that directly determines the reaction rate is the rate at which the reactants are consumed and the products are formed.

Thus, the rate of a reaction is determined by how quickly the reactants disappear and the products appear, which in turn is influenced by the various factors that affect the frequency of successful collisions between the reacting molecules.

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Metals are generally associated with the highest density values at room temperature.

A metals is a substance that, when freshly prepared, polished, or broken, exhibits a brilliant look and conducts electricity and heat quite well (from the Greek word métallon, "mine, quarry, metal"). Typically, metals are malleable and ductile (can be drawn into wires) (they can be hammered into thin sheets). These characteristics are the outcome of the metallic link that exists between the metal's atoms or molecules.A metal can be a chemical element like iron, an alloy like stainless steel, a molecular complex like polymeric sulphur nitride, or any combination of these.

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Answer:

Filtration is a method for separating an insoluble solid from a liquid. When a mixture of sand and water is filtered: the sand stays behind in the filter paper (it becomes the residue ) the water passes through the filter paper (it becomes the filtrate )

Explanation:

Answer:

Describe the best method for separating a mixture of sand, salt, and steel shavings by placing the steps below in the correct order.

⇒ 4 Heat the mixture to evaporate the water.

⇒ 3 Pour the mixture through a filter to separate the sand.

⇒ 1 Pass a magnet over the mixture to remove the steel.

⇒ 2 Add water to the sand/salt mixture and stir to dissolve the salt.

Answer:

One of the most viscous liquids known is pitch, also known as bitumen, asphalt, or tar.

Explanation:

This is the answer

Answer:

\(3Ca(OH)_{2} + 2H_3PO_4 ==> Ca_3(PO_4)_2 + 6H_2O\)

Explanation:

The chemical equation represented as:

\(2H_3PO_4 (aq)+ 3Ca (OH)_2 (aq) ----- > Ca(PO_4)_2 (s)+ 6H_2O (l)\)

A chemical equation is defined as a symbolic representation of a chemical reaction in the form of symbols and chemical formulas. Coefficients that are used in front of reactants and products to balance the equation to show that matter is conserved.

Representation of chemical reactions by symbols and formulas of substances is called chemical equation. In this equation A and B are called reactants and C and D are called products while the arrow shows the direction of the chemical reaction.

For the above given information,

\(2H_3PO_4 (aq)+ 3Ca (OH)_2 (aq) ----- > Ca(PO_4)_2 (s)+ 6H_2O (l)\)

Phosphoric      Calcium                               Calcium          Water

acid                hydroxide                            phosphate

Where, Aqueous phosphoric acid and aqueous calcium hydroxide are reactants and solid calcium phosphate and water are products.

Thus, the chemical equation represented as:

\(2H_3PO_4 (aq)+ 3Ca (OH)_2 (aq) ----- > Ca(PO_4)_2 (s)+ 6H_2O (l)\)

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Answer:

Carbon=about 85.13%

Hydrogen=about 14.26%

Explanation:

Percent composition= (molar mass of element x amount of it)/Molar mass x100

C= 12x3/42.08 x100=about 85.13

H=6x1/42.08 =about 14.26

Just putting a comment here, I needed to test something